Color blindness in humans: causes, how to check

Color blindness is a special type of visual impairment, which is manifested in the absence of perception of certain colors, most often green, red and purple. Basically, color blinds are not able to distinguish a particular color or several colors. But there are also types of color blindness, when the patient does not identify a single color - a complete color blindness. Theoretically, only men are affected by this violation. However, statistics say that 0.4-0.5% of women suffer color blindness due to various retinal injuries.

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Causes of the color blindness

There are two reasons for the appearance of color blindness:

• Heredity

Color blindness is linked to the X chromosome and transmitted from the mother to the child. Often there are cases of inherent distortion of perception of some flowers, but the patient can recognize and distinguish other colors and shades that are difficult to distinguish for an ordinary person. About cases of color blindness in women, read this article.

• Retinal Injury

Color blindness develops against the background of damage to the retina of the eye and optic nerve.

In the center of the retina are special cells, the main function of which is the perception of color. These cells are called cones. Three kinds of cones are involved in the retina, each of which contains a protein substance (pigment) that captures its genetic embedded color: green, red or blue. The cones of a healthy person contain all three pigments. The cones in the pathology are devoid of pigment or it is defective.

• Pathology of the optic nerve

With neuritis and atrophy of the optic nerve, the color perception decreases, depending on the degree of damage to the visual analyzer.

• Age-related visual impairment associated with clouding the lens
• Consequences of taking certain medicines (digitoxin, ibuprofen)

The use of drugs based on digitalis causes visual impairment due to its accumulation in the blood plasma and the retina. The statistics say that 25% of the side effects of digitoxin intake are manifested in the disorder of vision and color perception (the appearance of blue-yellow or red-green spots in front of the eyes, the shining of objects with shades of yellow).

How is color blindness inherited?

Color blindness is inherited and manifested only in men. This is due to the fact that the gene for color blindness is linked to the X chromosome. As is known, female chromosomes are represented in the form of XX, and male in the form of XY. It follows that the defeat of the X chromosome in men inevitably causes the disease, while the defeat of the female X chromosome is compensated by another X chromosome, so the disease does not manifest itself. The woman acts in the role of the carrier of the disease, which she passes through the genotype to her children.

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Risk factors

The main risk factor is the presence of color blindness in close relatives, especially the mother.

The likelihood of color vision is significantly increased in people who have a history of mechanical trauma and retinal burns. Such aggressive effects can cause a sharp or gradual deterioration in color vision.

Color blindness can occur against the background of cardiac glycosides, prolonged and uncontrolled reception of non-steroidal anti-inflammatory drugs, as well as narcotic substances (hallucinogens cause first an aggravation of color vision, after which it may be weakened for some time).

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Symptoms of the color blindness

The main and only symptom is the inability to distinguish certain colors.

The first signs of hereditary color blindness can be found in adolescence, for example during a medical examination to obtain a driver's license. Congenital color blindness is perceived by the patient as a norm, as he is not aware of the presence of other colors.

In childhood, the only symptom of color blindness is the inability to distinguish the colors of surrounding objects. If you ask from the presented toys to choose red, the child will not cope with this task.

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Forms

Color blindness is of two types:

1. hereditary;
2. acquired.

Congenital color blindness is inherited from the mother carrier.

Acquired color blindness occurs against the background of eye injuries and disruption of the integrity of structures responsible for color recognition.

The inability to distinguish all colors is called monochrome color blindness. In this state, the patient sees the surrounding world in gray and black-and-white tones.

Full immunity to flowers is called achromasia. This kind of color blindness is very rare.

Partial color blindness is manifested in the inability to see one or two colors, for example green and red or blue and yellow spectral regions.

There is one more similar concept - "emotional color blindness". This term refers to psychiatry and is not related to vision. Emotional color blindness is the impossibility of a person to adequately perceive the whole variety of emotions. Such a person can appreciate emotion only in terms of good and bad.

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Complications and consequences

The consequences and complications of color blindness directly depend on the cause of its occurrence. Congenital color blindness can be at the same level for life. Acquired color blindness can develop into more severe pathologies in the absence of treatment and prevention.

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Diagnostics of the color blindness

To diagnose color blindness, Rubkin's tables are used . The tables show circles of different colors, but with the same brightness. From these circles there is a solid background and a geometric figure (figure) in the center of the table. A total of 27 cards are offered to the patient. The image that a healthy person sees is different from what a person with a visual impairment sees. The test is used to determine the type of color blindness.

Another informative study is the Ishirach test. The test also includes the use of special cards with drawings that can be recognized by a person with normal vision (90% of correct answers). A person with color-blindness will not be able to recognize images or will cope with the task in part (5 - 30% of correct answers).

The third method of diagnosis is spectral. Rabken's spectroanalamoscope is used for the study. This device has two color fields. One field is yellow, and the other field is red and green. The patient is offered to level the colors, so that red and green on the second field become yellow. The presence of color blindness prevents a normal assessment of the color gamut.

Using the above methods, a color blindness test is conducted for drivers.

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Differential diagnosis

Differential diagnosis is performed to exclude various types of retinopathy or retinal atrophy. In the first stages of the pathology of the retina can manifest itself in violation of color perception and have a symptomatology similar to color-blindness. Further the disease progresses, which can lead to partial or complete blindness. Diagnose with the help of ophthalmologic techniques and the collection of a family anamnesis.

Treatment of the color blindness

At the moment there is no special therapy for the treatment of color blindness. Scientists have put forward the theory of the advisability of applying genetic engineering by integrating the missing genes into the cellular apparatus of the retina. Such a technique will significantly improve color vision with a minimum probability of relapse.

In retinal dystrophies, taurine eye drops, vitamin B vitamins and AEV capsules are prescribed. These drugs in the complex improve the eye blood circulation, normalize the redox processes and trophic tissue.

There are special glasses from color blindness. Outwardly they look like ordinary sunglasses and are designed for everyday wear. Glasses of these glasses are multilayer lenses, which include a special substance - neodymium oxide. Glasses help people to distinguish colors in an optimal way, but do not have the potential of full-fledged vision.

Prevention

To prevent the occurrence of complications, it is necessary to regularly undergo a routine examination with the oculist and eliminate factors that adversely affect the retina (prolonged work at the computer, bright lights, taking certain drugs). The main goal of prevention is to avoid overexertion of the eyes.

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Color blindness and driver's license

Since 2000, the Ministry of Health issued a decree banning the management of vehicles of persons suffering from color blindness. This decision is argued by many factors that can cause an emergency.

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Color blindness and army

Color blindness is not included in the list of diseases that give the right to defer or release from the army.

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Where can I work with color blindness?

With the diagnosis of color blindness it is forbidden to work with any vehicles and mechanisms in which color perception is necessary. For other occupations, color blindness is not an obstacle.